"the early Solar System, but they either merged or were destroyed, leaving the planets, dwarf planets, and leftover minor bodies. Due to their higher boiling points, only metals and silicates could exist in solid form in the warm inner Solar System close to the Sun, and these would eventually form the rocky planets of Mercury, Venus, Earth, and Mars. Because metallic elements only comprised a very small fraction of the solar nebula, the terrestrial planets could not grow very large. The giant planets (Jupiter, Saturn, Uranus, and Neptune) formed further out, beyond the frost line, the point between the orbits"
"Gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are sometimes known as failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term ""gas giant"" was originally synonymous with ""giant planet"", but in the 1990s it became known that Uranus and Neptune are really a distinct class of giant planet, being composed mainly of heavier volatile substances (which are referred to as ""ices""). For this reason, Uranus and Neptune are now often classified in the separate category"
"it has the right temperature. Gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Gas giants are sometimes known as failed stars because they contain the same basic elements as a star. Jupiter and Saturn are the gas giants of the Solar System. The term ""gas giant"" was originally synonymous with ""giant planet"", but in the 1990s it became known that Uranus and Neptune are really a distinct class of giant planet, being composed mainly of heavier volatile substances (which are referred to as ""ices""). For this reason, Uranus and Neptune are now often"
"source for chemical abundance, despite their rareness (only five have been recovered on Earth). The planets of the Solar System are divided into two groups: the four inner planets are the terrestrial planets (Mercury, Venus, Earth and Mars), with relatively small sizes and rocky surfaces. The four outer planets are the giant planets, which are dominated by hydrogen and helium and have lower mean densities. These can be further subdivided into the gas giants (Jupiter and Saturn) and the ice giants (Uranus and Neptune) that have large icy cores. Most of our direct information on the composition of the giant"
"Giant planet A giant planet is any massive planet. They are usually primarily composed of low-boiling-point materials (gases or ices), rather than rock or other solid matter, but massive solid planets can also exist. There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus and Neptune. Many extrasolar giant planets have been identified orbiting other stars. Giant planets are also sometimes called jovian planets, after Jupiter (""Jove"" being another name for the Roman god ""Jupiter""). They are also sometimes known as gas giants. However, many astronomers now apply the latter term only to Jupiter and Saturn, classifying"
"These structures are huge storms. Some such spots are thunderheads as well. Giant planet A giant planet is any massive planet. They are usually primarily composed of low-boiling-point materials (gases or ices), rather than rock or other solid matter, but massive solid planets can also exist. There are four known giant planets in the Solar System: Jupiter, Saturn, Uranus and Neptune. Many extrasolar giant planets have been identified orbiting other stars. Giant planets are also sometimes called jovian planets, after Jupiter (""Jove"" being another name for the Roman god ""Jupiter""). They are also sometimes known as gas giants. However, many"
"matter may appear in. In the outer Solar System, hydrogen and helium are referred to as ""gases""; water, methane, and ammonia as ""ices""; and silicates and metals as ""rock"". Because Uranus and Neptune are primarily composed of, in this terminology, ices, not gas, they are increasingly referred to as ice giants and separated from the gas giants. Gas giants can, theoretically, be divided into five distinct classes according to their modeled physical atmospheric properties, and hence their appearance: ammonia clouds (I), water clouds (II), cloudless (III), alkali-metal clouds (IV), and silicate clouds (V). Jupiter and Saturn are both class I."
"HR 8799 e </math></ref> HR 8799 e is a large exoplanet, orbiting the star HR 8799, which lies 129 lightyears from Earth. This gas giant is between 5 and 10 times the mass of Jupiter, the largest planet in the Solar System. Due to their young age and high temperature all four discovered planets in the HR 8799 system are large, compared to all gas giants in the Solar System. HR 8799 e is the fourth planet orbiting HR 8799 in order of discovery. It is a young, hot and massive gas giant, and is fairly close to its star,"
"On March 13, 2007, Jet Propulsion Laboratory announced that it found strong evidence of seas of methane and ethane in the northern hemisphere. At least one of these is larger than any of the Great Lakes in North America. The American aerospace engineer and author Robert Zubrin identified Saturn as the most important and valuable of the four gas giants in the Solar System, because of its relative proximity, low radiation, and excellent system of moons. He also named Titan as the most important moon on which to establish a base to develop the resources of the Saturn system. Robert"
"Ice giant An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune. In astrophysics and planetary science the term ""ices"" refers to volatile chemical compounds with freezing points above about 100 K, such as water, ammonia, or methane, with freezing points of 273 K, 195 K, and 91 K, respectively (see Volatiles). In the 1990s, it was realized that Uranus and Neptune are a distinct class of giant planet, separate from the other giant planets,"
"landing on a giant planet may or may not be possible, depending on the size and composition of its core. Gas giants consist mostly of hydrogen and helium. The Solar System's gas giants, Jupiter and Saturn, have heavier elements making up between 3 and 13 percent of their mass. Gas giants are thought to consist of an outer layer of molecular hydrogen, surrounding a layer of liquid metallic hydrogen, with a probable molten core with a rocky composition. Jupiter and Saturn's outermost portion of the hydrogen atmosphere has many layers of visible clouds that are mostly composed of water and"
"originate in an ionized convecting fluid-ice mantle. Ice giant An ice giant is a giant planet composed mainly of elements heavier than hydrogen and helium, such as oxygen, carbon, nitrogen, and sulfur. There are two ice giants in the Solar System: Uranus and Neptune. In astrophysics and planetary science the term ""ices"" refers to volatile chemical compounds with freezing points above about 100 K, such as water, ammonia, or methane, with freezing points of 273 K, 195 K, and 91 K, respectively (see Volatiles). In the 1990s, it was realized that Uranus and Neptune are a distinct class of giant"
"the Gas Giant's Lagrangian point, 60° ahead on its orbit . It orbits the Sun at a distance of 4.9–5.5 AU once every 11 years and 9 months (4,301 days; semi-major axis of 5.18 AU). Its orbit has an eccentricity of 0.06 and an inclination of 11° with respect to the ecliptic. The body's observation arc begins with its official discovery observation at Palomar in September 1976. Fernando Roig and Ricardo Gil-Hutton identified ""Euryalos"" as the principal body of a small Jovian asteroid family, using the hierarchical clustering method (HCM), which looks for groupings of neighboring asteroids based on the"
"in mass. In 1952, science fiction writer James Blish coined the term ""gas giant"" and it was used to refer to the large non-terrestrial planets of the Solar System. However, in the 1990s, the compositions of Uranus and Neptune were discovered to be significantly different from those of Jupiter and Saturn. They are primarily composed of elements heavier than hydrogen and helium, constituting a separate type of giant planet altogether. Because during their formation Uranus and Neptune incorporated their material as either ices or gas trapped in water ice, the term ""ice giant"" came into use. Modelling the formation of"
"same composition as the Sun, but the planets could also have formed when a solid core captured nebular gas. In current models, the four giant planets have cores of rock and ice that are roughly the same size, but the proportion of hydrogen and helium decreases from about 300 Earth masses in Jupiter to 75 in Saturn and just a few in Uranus and Neptune. Thus, while the gas giants are primarily composed of hydrogen and helium, the ice giants are primarily composed of heavier elements (O, C, N, S), primarily in the form of water, methane and ammonia. The"
"different forms of heat transfer and mixing. Furthermore, gas giants show different heat effects by size and distance to the Sun. Uranus shows a net negative heat budget to space, but the others (including Neptune, farther out) are net positive. Two terrestrial planets (Earth and Mercury) display magnetospheres, and thus have molten metal layers. Similarly, all four gas giants have magnetospheres, which indicate layers of conductive fluids. Ganymede also shows a weak magnetosphere, taken as evidence of a subsurface layer of salt water, while the volume around Rhea shows symmetrical effects which may be rings or a magnetic phenomenon. Of"
"Jupiter and Saturn. They have become known as ""ice giants"". Their constituent compounds were solids when they were primarily incorporated into the planets during their formation, either directly in the form of ices or trapped in water ice. Today, very little of the water in Uranus and Neptune remains in the form of ice. Instead, water primarily exists as supercritical fluid at the temperatures and pressures within them. Ice giants consist of only about 20% hydrogen and helium in mass, as opposed to the Solar System's gas giants, Jupiter and Saturn, which are both more than 90% hydrogen and helium"
"Hot Jupiters are class IV or V. A cold hydrogen-rich gas giant more massive than Jupiter but less than about () will only be slightly larger in volume than Jupiter. For masses above , gravity will cause the planet to shrink (see degenerate matter). Kelvin–Helmholtz heating can cause a gas giant to radiate more energy than it receives from its host star. Although the words ""gas"" and ""giant"" are often combined, hydrogen planets need not be as large as the familiar gas giants from the Solar System. However, smaller gas planets and planets closer to their star will lose atmospheric"
"Uranus Uranus (from the Latin name ""Ūranus"" for the Greek god Οὐρανός) is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. Uranus is similar in composition to Neptune, and both have bulk chemical compositions which differ from that of the larger gas giants Jupiter and Saturn. For this reason, scientists often classify Uranus and Neptune as ""ice giants"" to distinguish them from the gas giants. Uranus' atmosphere is similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, but it contains more ""ices"" such as"
"candidate sites had little or no possibility of being the results of the proposed impacts. More recent discoveries include the following: Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a giant planet with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined. Jupiter and Saturn are gas giants; the other two giant planets, Uranus and Neptune, are ice giants. Jupiter has been known to astronomers since antiquity. It is named after the Roman god Jupiter. When viewed from"
"gas giants Jupiter and Saturn. It has a temperature of , around that of the surface temperature of Venus. It has an estimated mass of around 5.3 and a potential radius of around 9% larger than Jupiter (1.11 , or 12.2 ) based on its mass, since it is more massive than the jovian planet. The planet orbits a (K-type) giant star named HD 240237. It has exhausted the hydrogen supply in its core and is currently fusing helium. The star has a mass of 1.69 and a radius of around 32 . It has a surface temperature of 4361K"
"to reflection by the cloud decks. At such temperatures, a gas giant may glow red from thermal radiation but the reflected light generally overwhelms thermal radiation. For stars of visual apparent magnitude under 4.50, such planets are theoretically visible to our instruments. Examples of such planets might include 51 Pegasi b and Upsilon Andromedae b. HAT-P-11b and those other extrasolar gas giants found by the Kepler telescope might be possible class V planets, such as Kepler-7b, HAT-P-7b, or Kepler-13 b. Sudarsky's gas giant classification Sudarsky's classification of gas giants for the purpose of predicting their appearance based on their temperature"
"the terrestrial and gas giants is relatively straightforward and uncontroversial. The terrestrial planets of the Solar System are widely understood to have formed through collisional accumulation of planetesimals within the protoplanetary disc. The gas giants—Jupiter, Saturn, and their extrasolar counterpart planets—are thought to have formed after solid cores around 10 Earth masses () formed through the same process, while accreting gaseous envelopes from the surrounding solar nebula over the course of a few to several million years (Ma), although alternative models of core formation based on pebble accretion have recently been proposed. Some extrasolar giant planets may instead have formed"
"5,000 years. A gas giant planet, home to a species of airborne amoebas. The supposed home planet of the Kiint (it is actually a research station; in truth their home is a ring system of inhabitable worlds, located in another galaxy). Jobis has three moons orbiting the Lagrange One point, rotating around a common centre. This triad was created deliberately by the Kiint in what they called an old experiment. The planet is not heavily populated. Syrinx visited Jobis to question the Kiint concerning their knowledge of possession. Largest gas giant in the Sol system. Eden and multiple other Edenist"
"show evidence of Methane and Acetylene but no Ammonia or Carbon Dioxide. There is currently no explanation why this planet shows strong methane absorption, but the other 3 planets in this system do not, despite all 4 planets having similar atmospheric temperatures. HR 8799 e </math></ref> HR 8799 e is a large exoplanet, orbiting the star HR 8799, which lies 129 lightyears from Earth. This gas giant is between 5 and 10 times the mass of Jupiter, the largest planet in the Solar System. Due to their young age and high temperature all four discovered planets in the HR 8799"
"Uranus and Neptune are far less massiveless than 20 Earth masses () eachand are composed primarily of ices. For these reasons, some astronomers suggest they belong in their own category, ice giants. All four giant planets have rings, although only Saturn's ring system is easily observed from Earth. The term ""superior planet"" designates planets outside Earth's orbit and thus includes both the outer planets and Mars. The centaurs are icy comet-like bodies whose orbits have semi-major axes greater than Jupiter's (5.5 AU) and less than Neptune's (30 AU). The largest known centaur, 10199 Chariklo, has a diameter of about 250"
"years, as opposed to the similarly sized Great Red Spot of Jupiter, which has persisted for centuries. Of all known giant planets in the Solar System, Neptune emits the most internal heat per unit of absorbed sunlight, a ratio of approximately 2.6. Saturn, the next-highest emitter, only has a ratio of about 1.8. Uranus emits the least heat, one-tenth as much as Neptune. It is suspected that this may be related to its extreme 98˚ axial tilt. This causes its seasonal patterns to be very different from those of any other planet in the Solar System. There are still no"
"the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that"
"days and two outer gas giants with periods of 2.6 and 6 years respectively. HD 196050 and HD 175167 are yellow G-class Sun-like stars, while HD 190984 is an F-class main sequence star slightly larger and hotter than the Sun; all three are accompanied by a gas giant companion. HD 172555 is a young white A-type main sequence star, two planets of which appear to have had a major collision in the past few thousand years. Spectrographic evidence of large amounts of silicon dioxide gas indicates the smaller of the two, which had been at least the size of Earth's"
"their modeled physical atmospheric properties. In the Solar System, only Jupiter and Saturn are within the Sudarsky classification, and both are Class I. The appearance of planets that are not gas giants cannot be predicted by the Sudarsky system, for example terrestrial planets such as Earth and Venus, HD 85512 b (3.6 Earth masses) and OGLE-2005-BLG-390Lb (5.5 Earth masses), or ice giants such as Uranus (14 Earth masses) and Neptune (17 Earth masses). The appearance of extrasolar planets is largely unknown because of the difficulty in making direct observations of extrasolar planets. In addition, analogies with planets in the Solar"
"Galilean moons The Galilean moons are the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in January 1610, and recognized by him as satellites of Jupiter in March 1610. They were the first objects found to orbit another planet. Their names derive from the lovers of Zeus. They are among the largest objects in the Solar System with the exception of the Sun and the eight planets, with a radius larger than any of the dwarf planets. Ganymede is the largest moon in the Solar System, and is even bigger than the"
"infrared spectra are telltale signs of brown dwarfs. Some emit X-rays; and all ""warm"" dwarfs continue to glow tellingly in the red and infrared spectra until they cool to planet-like temperatures (under 1000 K). Gas giants have some of the characteristics of brown dwarfs. Like the Sun, Jupiter and Saturn are both made primarily of hydrogen and helium. Saturn is nearly as large as Jupiter, despite having only 30% the mass. Three of the giant planets in the Solar System (Jupiter, Saturn, and Neptune) emit much more heat than they receive from the Sun. And all four giant planets have"
"Sudarsky's gas giant classification Sudarsky's classification of gas giants for the purpose of predicting their appearance based on their temperature was outlined by David Sudarsky and colleagues in the paper ""Albedo and Reflection Spectra of Extrasolar Giant Planets"" and expanded on in ""Theoretical Spectra and Atmospheres of Extrasolar Giant Planets"", published before any successful direct or indirect observation of an extrasolar planet atmosphere was made. It is a broad classification system with the goal of bringing some order to the likely rich variety of extrasolar gas-giant atmospheres. Gas giants are split into five classes (numbered using Roman numerals) according to"